Motor starter



Oct. 9, 1928. 1,686,772

E. w. SEEGER MOTOR STARTER Filed April 23, 1925 1 2 L L 571%. 1. 10 f A6 18 4, ll 12 L r, 15 5 s 18 17% INVENTOR 84mm 'miwg/e/v.

ATTORNEY Patented Oct. 9 1928 UNITED STATES PATENT OFFICE.

ASSIGNOR TO THE CUTLER-HAH- CORIPORATION OF "WISCONSIN.

MOTOR STARTER.

Application filed April 23, 1923. Serial No. 633,834.

This invention relates to motor starters.

Motorstarters commonly include a starting switch for connecting the motor to a supply circuit through a protective element and a running switch for connecting the motor directly to the supply circuit. It has been proposed to time the operation of the running switch by electro-thermally controlled means but heretofore such means did not insure roper timing characteristics upon starting of the motor under widely varying loads. For example, it has been proposed to employ electro-thermal timing means in connection with auto-transformer starters but dueto the fact that such timing means is energized by current through the transformer only slight variations in the starting period are obtained upon wide variations in the time required to bring the motor up to speed;

The present invention has among its objects to provide a starting controller including electro-thermally controlled timing means which is adapted to vary the starting period in accordance with the time required to bring the motor up to speed and to also insure establishment of the running connections after a given period upon failure of the motor to start.

Another object is to provide a resistance controller of the aforesaid character which is adapted for control of both A. G. and D. C. motors.

Various other objects and advantages of 4 the invention will hereinafter appear.

The accompanying drawing illustrates certain embodiments of the invention which will now be described, it being understood that the embodiments illustrated are susceptible of modification without departing from the scope of the appended claims.

In the drawing,

Figure 1 is a diagrammatic view of a controller embodying the invention; and

Fig. 2 is a modification of the controller illustrated in Fig. 1.

Referring to Fig. 1 the same illustrates a motor M to be supplied with current from lines L and L starting resistances R and R and a controller including electromagnetic switches 1 and 2, the former switch being responsive to establish power connections through said resistances for starting and the latter being responsive to establish power connections exclusive of said resistances for running.

Starting switch 1 is controlled through the medlum of a normally open push button switch 3 and a normally closed push button switch 4, and the same is provided with normally open auxiliary maintaining contacts 5. Running switch 2 is provided with normally closed auxiliary contacts 6 and 7 and the energizing circuit thereof is controlled by push button switch 4, auxiliary contacts 5 and 6 and an electro-thermal timing device 8. Timmg device 8 is preferably of a type disclosed and claimed in a patent of Erwin R. Stoekle, No. 1,4 88,951, dated April 1, 1924, and comprises in its essential aspects an insulating conta ner having electrodes enetrating therein and normally connected y a quant1t y of mercury. Said container is provided with a reduced portion located between the aforementioned electrodes and said reduced portion is surrounded by or otherwise associated with an electrical heating element 9. Heating element 9 is normally connected through contacts 7 across the terminals of motor M and the arrangement is such that upon a predetermined heating effect the mercury within the reduced portion of the container becomes vaporized with a consequent sudden interruption of the electrical continuity of the mercury column contained therein whereby circuit between the electrodes is interrupted. Said device is moreover inherently adapted to reset automatically upon cooling thereof.

The operation of the controller and the various circuits involved will now be more fully described. Closure of switch 3 establishes an energizing circuit for starting switch 1 extending from line L by conductor 10 through push button switches 3 and 4 by conductors 11 and 12 through the operating winding 1 and by conductor 13 to line L Switch 1 in responding maintains itself by a circuit extending from line L by conductors 10 and 14 through auxiliary contacts 5 by conductor 15 to and through push button switch 4 and thence through the operating winding 1 to line L as already traced. Upon closure of switch 1, the left hand terminal of motor M is connected to line L through resistance R and the right hand terminal of said motor is connected to line L through resistance R". Also upon closure of switch 1 winding 2 of switch 2 is connected across lines LL by a circuit extendin from lme by conductors 10 and 14 through auxiliary contacts 5 by conductor 15 through push button switch 4 and by conductors 11 and 16 to the left hand terminal of said winding and from the right hand terminal ofsaid winding by conductor 17, through a resistance 7 and by conductor 18 to line L However, switch 2 does not respond immediately due to shortcircuiting of the winding 2*- through mercury switch 8, said short-circuit extendin from the left hand terminal of winding 2 by conductor 19 through auxiliary contacts 6 by conductor 20 through mercury switch 8 by conductor 21 through resistance 1', and by conductor 18 to line L Assuming that motor M starts upon closure of switch 1, the terminal Voltage thereof will increase as the motor speeds up. Heating coil 9 is subjected to such terminal voltage the same having its upper terminal connected through auxiliary contacts 7 to the right hand terminal of motor M and its lower terminal directly connected to the left hand terminal of said motor. Thus during starting of the motor the heating effects produced by coil 9 will vary with the rate of acceleration of the motor and said heating coil will therefore effect response of mercury switch 8 after a period of time determined by the rate of acceleration of the motor. In responding switch 8 interrupts the aforedescribed short circuit around coil 2 whereupon switch 2 will respond to connect the motor directly to lines L and L, the circuit connections through switch 2 being obvious from the drawing. Upon failure of motor M to start heating coil 9 will be subjected to a relatively low voltage but after a given period the same will effect response of switch 8 for establishment of the running connections. Further it should be noted that by including or excluding portions of the starting resistance in the circuit of heating coil 9, the heating effects produced thereby can be varied as desired. Upon response of switch 2 the same disconnects heating coil 9 from the terminals of the motor through opening of auxiliary contacts 7 and also insures against re-establishment of the aforedescribed short circuit around winding 2*, through opening of auxiliary contacts 6.

Referring to Fig. 2 the same illustrates a modification of the controller shown in Fig. 1, the heating coil 9 being arranged to time response of switch 2 through the medium of a thermostatic strip 22. The thermostatic strip 22 is normally in open position and upon given heating effects produced by heating coil 9 the same is adapted to respond to establish an en- 'ergizing circuit for switch 2 extending from line L by conductors 10 and 14 through auxiliary contacts 5 of switch 1 by conductor 15 through push button switch 4, by conductors 11, 16 and 23 through thermostatic strip 22 by conductor 24 through winding 2 and byconductors 25 and 18 to line L In responding switch 2 is adapted to maintain itself by a circuit extending from line L to conductor 16 as already traced through normally open auxiliary contacts 26 and thence through the winding 2 to line L as already traced.

What I claim as new and desire to secure by Letters Patent is l. The combination with a motor, of potential reducing means to be included in circuit therewith for starting, means to establish starting connections and running connections progressively, and a thermal device to effect operation of the latter means for establishment of running connections subject to delay pending a given operation of said device, said device having a heating coil and connections therefor to effect the aforementioned operation of said device within a given period after establishment offstarting connections even though the motor fails to accelerate and to render such period variable by acceleration of the motor therewithin.

2. The combination with a motor, of potential reducing means to be included in circuit therewith for starting, means to establish progressively starting and running connections for said motor, and a thermal device to effect operation of the latter means for establishment of running connections subject to delay pending a given operation of said device, said device having a heating coil and connections subjecting said coil to a voltage Variable in accordance with the counterelectromotive force of said motor and sufficient at standstill of said motor to cause said device to operate within a given time after establishment of starting connections even though the motor fails to accelerate.

3. The combination with a motor, of starting resistance therefor, and'means to establish progressively starting connections for said motor inclusive of said resistance and running connections exclusive of said resistance, and a thermal device to effect operation of the latter means for establishment of running connections subject to delay pending a given op eration of said device, said device having a heater coil connected across the terminals of the motor and shunting part of said resistance.

4. The combination with a motor, or potential reducing means,'means to establish starting connections for said motor, inclusive of said potential reducing means, a thermal device having a heating coil to effect actuation thereof and having connections for said coil whereby it is influenced by acceleration of the motor and is subjected to a voltage at standstill of the motor sufficient to cause operation of said device within a given period after establishment of starting connections and means responsive upon Operation of said device to establish running connections for said motor.

5. The combination with a motor, of starting resistance therefor, means for establishing starting connections for said motor including said resistance, a thermal device having a heating coil to effect operation thereof and having said coil connected across the terminals of said motor and in shunt with part of 0 In witness whereof, I have hereunto sub- 15 scribed my name.

EDWIN W. SEEGER. 

